LIFE SCIENCE

Detailed explanation-1: -Introduction. 5-Bromouracil (BrU) is a base analogue of thymine (T) which can be incorporated into DNA. It is a well-known mutagen, causing transition mutations by mispairing with guanine (G) rather than pairing with adenine (A) during replication.

Detailed explanation-2: -However, 5 bromouracil pairs with thymine because the analog of thymine has a higher tendency to form an enol tautomer with its resembling base that is thymine. The enol tautomer pairing of 5-bromouracil causes the transition of T-A to C-G thus changing the base sequence of DNA.

Detailed explanation-3: -Base Analogs That Alter Base Pairing Preference 2-AP is an adenine analog and it usually pairs with thymine, but it can also form pairs with cytosine, causing both AT-to-GC and GC-to-AT transition mutations. Some chemicals covalently modify existing bases, causing mispairing during subsequent replication.